The invention relates to a device and a method for damping pressure fluctuations in a delivery line of a thick-matter piston pump, comprising at least one container which communicates with the delivery line and is at least partially filled with a compressible fluid, for the pulsing intake and delivery of transported material during the pumping operation of the thick-matter pump with alternating compression and expansion of the fluid.
Thick-matter or concrete piston pumps, mainly in the form of two-piston pumps, exhibit a function-related delivery gap during the switch-over from the intake stroke to the pressure stroke, and vice versa. For a short period of time lasting roughly 0.2 to 1 second, depending on the size of the machine, there is no material flow and the pressure in the delivery line briefly plummets. This brief interruption in the delivery flow with a corresponding drop in pressure causes knocking and high mechanical loads in the delivery line. This may result in material fatigue and premature failure. For this reason, there are different approaches to minimizing pressure drops of this kind by means of damping measures. Diaphragm dampers or hose dampers are used, for example, although they only work optimally over a small pressure range and are subject to a high degree of wear due to the moving rubber diaphragm, particularly when abrasive material is being transported. There is therefore a need for a damping system which has a simple construction, can be economically realized and works reliably when operated with the transported material used, for example thick-matters such as concrete, tailings, fly ash, slurry and the like, and is low-wear.
A known damping device is the so-called air vessel, in which a container, usually in the form of a vessel or pipe, installed on the suction and/or pressure side of the pump and preloaded with gas, delivers its stored energy during the delivery gap and thereby helps to reduce said delivery gap. This is a standard system in piston-diaphragm or plunger pumps, with which low-pulsation operation can be achieved. Although the air vessel combined with two-piston thick-matter pumps does not guarantee a completely continuous delivery flow, it dampens the pressure drops and, as a consequence, the pipeline knocking to an acceptable degree.